1. Field of the Invention
This invention relates to a wireless communication apparatus and its communication method.
2. Description of the Related Art
In recent years, electronic devices with a wireless communication function have been widely used. They include notebook-size personal computers (notebook PCs), game machines, car navigation systems, digital cameras, and personal digital assistants. Wireless LAN communication complying with the IEEE 802.11 standard and Bluetooth communication (registered trademark) are well known as wireless communication methods used in electronic devices with wireless communication functionality.
Wireless-LAN (IEEE 802.11b/g) and Bluetooth (IEEE 802.15.1) both use the 2.4-GHz frequency band. However, there is no interchangeability between the wireless methods (Wireless-LAN (IEEE 802.11b/g) and Bluetooth (IEEE 802.15.1)). Therefore, in an environment where wireless communication devices differing in communication method are close to one another, they communicate using the same frequency band in the same time period, which results in radio wave interference. This causes the problem of degrading the communication performance.
Specifically, the problem occurs when a plurality of devices which have the function of implementing different wireless communication methods are arranged closed to one another in the same device, such as a notebook PC or a personal digital assistant, or when they are installed in the same system LSI (Large-scale Integrated circuit).
As for a conventional method of alleviating the degradation of the communication performance, Jpn. Pat. Appln. KOKAI Publication No. 2004-363728 and Jpn. Pat. Appln. KOKAI Publication No. 2005-45330 have disclosed a method of, when IEEE 802.11b/g/n and Bluetooth (a registered trademark) mounted in the same device perform communication simultaneously, monitoring the communication state of each wireless function and, if one function is communicating, inhibiting the other from communicating.